Bird Habitat and Populations in Oak Ecosystems of the Pacific Northwest

Home , Georgia Depression, Lazuli bunting, Manzanita, Western wood pewee

Land Manager’s Guide to Bird Habitat and Populations in Oak Ecosystems of the Pacific Northwest

— Bob Altman and Jaime L. Stephens

Oak Bird Guide • 1 Bob Altman

Acknowledgments Funding for this document was provided by the U.S. Fish and Wildlife Service through the Neotropical Mi- gratory Bird Conservation Act. The grant was part of the project Quercus and Aves V: Expanding Habitat Protection,Restoration,Science and Outreach for Bird Conservation in Oak Habitats of the Pacific Northwest. Reviews of earlier drafts were provided by J. Morrison, M. Morrison, J. Nielson, G. Radko, and G. Shire. Layout and design by G. Radko. Unpublished bird data were provided by J. Alexander, E. Delvin, J. Evans, K. Foley, W. Gross, I. Gruhn, K. Halstead, K. McAllister, R. Thompson, K. Viste-Sparkman, D. Vroman, and K. Weil.

Recommended Citation Altman, B. and J. L. Stephens. 2012. Land Managers Guide to Bird Habitat and Populations in Oak Ecosystems of the Pacific Northwest. American Bird Conservancy and Klamath Bird Observatory. 82 pp.

American Bird Conservancy (ABC) is a non-profit organization whose mission is to conserve native wild birds and their habitats throughout the Americas. ABC acts across the full spectrum of conservation issues to safeguard the rarest species, restore habitats, and reduce threats, while unifying and strengthening the bird conservation movement. ABC advances bird conservation through direct action and by finding and engaging the people and groups needed to succeed. Visit www.abcbirds.org for more information.

The mission of theU. S. Fish and Wildlife Service (USFWS) is working with others to conserve, protect, and enhance fish, wildlife, and plants and their habitats for the continuing benefit of the American people. Funding received from the USFWS for this project does not indicate that it is a USFWS product or imply complete endorsement of the contents.

Klamath Bird Observatory (KBO) advances bird and habitat conservation through science, education, and partnerships. Working in Klamath-Siskiyou Bioregion of southern Oregon and northern California, KBO conducts long-term monitoring and applied research projects that provide results that inform conservation and natural resource management decisions. KBO education programs teach students of all ages about birds as indicators of the healthy ecosystems on which we al depend. KBO broadens the effectiveness and scope of its science and education programs through collaboration with an array of partners. Visit www.KlamathBird.org for more information.

Cover photos, left to right: Lazuli Bunting: Greg Lavaty; Acorn Woodpecker: James Livaudais; Chipping Sparrow: Alan Wilson. Background photo: Bob Altman Table of Contents Oak Ecosystems in the Pacific Northwest...... 5 Geographic Scope...... 5 Changes and Threats...... 5 Ecoregions and Oak Habitats...... 7 Georgia Depression...... 7 Puget Lowlands...... 8 Willamette Valley...... 8 Klamath Mountains...... 8 East-slope Cascades...... 8 Oak Habitat Types...... 8 Oak Savannah...... 8 Oak Woodland Open...... 9 Oak Woodland Closed...... 9 Oak Forest...... 9 Oak/Pine...... 9 Oak/Fir...... 9 Oak/Hardwood...... 10 Oak/Chaparral...... 10 Riparian Oak...... 10 Oaks and Birds...... 11 Large Trees...... 11 Acorns...... 12 Dead Wood/Cavities...... 12 Tree Structure...... 12 Shrubs...... 13 Oak Bird Species...... 15 Priority and Focal Bird Species...... 16 Density Estimates...... 21 Response to Habitat Restoration and Management...... 23 Canopy...... 23 Sub-canopy and Understory...... 23 Literature Cited...... 26 Appendix A. Oak Bird Species Accounts...... 29 Acorn Woodpecker...... 30 Ash-throated Flycatcher...... 32 Bewick’s Wren...... 34 Black-capped Chickadee...... 36 Black-headed Grosbeak...... 38 Black-throated Gray Warbler...... 40 Blue-gray Gnatcatcher...... 42 Bushtit...... 44

Oak Bird Guide • 3 California Towhee...... 46 Cassin’s Vireo...... 48 Chipping Sparrow...... 50 Downy Woodpecker ...... 52 House Wren...... 54 Hutton’s Vireo...... 56 Lazuli Bunting...... 58 Lesser Goldfinch...... 60 Oak Titmouse...... 62 Nashville Warbler ...... 64 Purple Finch...... 66 Spotted Towhee...... 68 Western Bluebird...... 70 Western Scrub-jay...... 72 Western Tanager...... 74 Western Wood-pewee...... 76 White-breasted Nuthatch...... 78 Appendix B. Data Sources for Oak Bird Species Accounts...... 80 List of Figures Figure 1. Ecoregions with Oak Habitats in the Pacific Northwest...... 6 Figure 2. Degree of Occurrence of Bird Species Across the Gradient of Prairie-Oak Habitat Types...... 18 List of Tables Table 1. Summary of breeding season habitat relationships of oak-associated bird species in the Pacific Northwest...... 14 Table 2. Oak-associated bird species designated as being of conservation concern by the primary wildlife natural resource agencies in the Pacific Northwest...... 16 Table 3. Focal species habitat associations by ecoregion/sub-region for oak habitats in the Pacific Northwest...... 20 Table 4. Ecoregion/sub-region mean density estimates (birds/ha) for oak-associated bird species in oak-dominant habitats in the Pacific Northwest...... 22 Table 5. Projected potential bird species short-term population response to canopy management in oak habitats...... 24 Table 6. Projected potential bird species short-term population response to sub-canopy and understory management in oak habitats...... 25 List of Sidebars Purpose of the Oak Bird Guide...... 5 Quercus and Aves...... 7 The Rogue Basin and Oak Bird-Habitat Relationships...... 11 Patch Size and Edge Habitat...... 13 Oak Habitat Conservation for Resident and Cavity-Nesting Birds...... 15 Oak Bird-Habitat Relationships Summaries...... 16 Lewis’s Woodpecker: Poster Bird for Oak Savannah Conservation...... 17 Using Focal Species in Conservation Planning and Implementation...... 19 Focal Species and Effectiveness Monitoring...... 19

4 • Oak Bird Guide Oak Ecosystems in the Pacific Northwest Oak ecosystems in the Pacific Northwest are relatively dry environments scattered across a large landscape that is dominated by dense coniferous rainforests. This unique- ness represents an important component of regional biodiversity, featuring a high degree of habitat specialization by bird species.1 Oak ecosystems often occupy a transitional zone between prairies and conifer forests. Their existence and persistence depends on a complex mix of geological and ecological 2

processes, as well as culture, climate, and economics. The Bob Altman near-exclusive oak tree species in the Pacific Northwest is Purpose of the Oak Bird Guide: This Oak Bird Guide is the Oregon white oak, except for the southern Willamette intended to provide land managers in oak habitats with Valley ecoregion where some black oaks occur, and the information on bird species’ status, distribution, density, Klamath Mountains ecoregion where black oak is com- habitat relationships, and potential responses to oak habi- mon along with some canyon live oaks.3 tat management or restoration activities. This information can be used to facilitate sound decisions to support bird Most oak habitats today were created as a result of a man- conservation in the context of protection and manage- aged fire regime that ended with European settlement in ment of the unique and threatened oak ecosystems of the the mid 1800s. Historic burning by indigenous peoples Pacific Northwest. was a major factor that maintained oak habitats in many parts of the region.4 Frequent, low-intensity fires favor oaks which are fire-tolerant (especially mature trees), exclude portions of the East-slope Cascade Mountains ecoregion conifers such as Douglas-fir which are fire-intolerant, and in Oregon and Washington, and the Georgia Depression reduce the understory of shrubs and small trees. Thus, the ecoregion in British Columbia (Figure 1). historic condition in fire-maintained oak habitats was widely spaced, heavily branched, large, open-grown oak Changes and Threats trees with a park-like understory dominated by fire-toler- Changes to oak habitats in the Pacific Northwest have ant grasses and forbs and some scattered shrubs and small been profound. In British Columbia, <5% of pre-Eu- trees.5 In the absence of fire, oak habitats typically succeed ropean settlement oak habitat remains.6 In Washing- to conifer forest except in the driest areas where conifer ton on Joint Base Lewis McChord Military Installa- trees cannot survive. Some examples of these non-fire tion, which contains approximately 35% of the oak in maintained oak communities include south-facing rocky the Puget Lowlands ecoregion,7 <35% of pre-settlement slopes found throughout the region and glacial soils found oak habitat remains.8 In the Willamette Valley of Ore- in the south Puget Lowlands ecoregion. gon, only 20% of the historic oak woodlands and savannah remains,9 including <1% of the pre-settlement oak Geographic Scope savannah.10 This Oak Bird Guide covers Pacific Northwest oak Threats to oak habitats in the Pacific Northwest are ex- ecosystems from their northern extent along the tensive and diverse. Most of the lowland and foothill oak southeastern portion of Vancouver Island, British habitats have been either eliminated by land development Columbia, south to the Oregon-California border, and or agriculture, or ecologically degraded by invasive vegeta- east along the Columbia River and the east-slope of the tion (e.g., Douglas-fir, non-native hawthorne, Himalayan Cascade Mountains in localized areas of central and south- blackberry, Scotch broom).2 Where oak habitats occur in central Washington and north and south-central Oregon. montane forests (e.g., East-slope Cascades, and Rogue This primarily includes the Puget Lowlands, Willamette Basin of southwest Oregon), oak habitats have been elim- Valley, and Klamath Mountain’s ecoregions, along with inated for timber production of faster growing conifers,

Oak Bird Guide • 5 Figure 1. Ecoregions with Oak Habitats in the Pacific Northwest

B R I T I SH C O L U M B I A

V a n c o u v e r Is la nd

San Juan Islands North Skagit Cascades Valley

Olympic Seattle Peninsula

Ecoregions South Puget El lensburg Eastern Cascades Sound Slopes and Foothills Klamath Mountains WA S H I N G T O N Puget Lowland Willamette Valley Eastern Cascades Georgia Depression

0 15 30 North Portland Cartography by Oregon CORE GIS LLC Coast Kilometers www.coregis.net

July 2012 Willamette Data: US EPA, Valley Cascade BC MoE Mountains

Bend Eugene

South O R E G O N Oregon Coast

Umpqua Valley

Eastern Cascades

Rogue Valley

6 • Oak Bird Guide Quercus and Aves: American Bird Conservancy, in partnership with numerous other organizations and agencies, has been leading the effort Greg Lavaty for bird conservation in oak communities in the Pacific Northwest since 2000 through its Quercus and Aves Program. The goal of this program is “full-spectrum and full life-cycle” that is, address all the important components of bird conservation in oak habitats, and do it both in the Pacific Northwest breeding grounds and in Mexico and Central America where most of the migratory bird species winter. Thanks to funding from the USFWS’ Neotropical Migratory Bird Conservation Act grant program and matching funds from our many partners, millions of dollars

have been raised to support this work. Accomplishments include three Black-throated Gray Warbler land acquisitions in south-central Washington for Lewis’s Woodpecker (approximately 1,000 acres) and three acquisitions in El Salvador (approximately 120 acres); nearly 40,000 acres of Private Reserves (land committed to conservation) in Guatemala and Costa Rica including one 24,000 acre tract of primary forest; habitat management and restoration (e.g., invasive species control, thinning, planting, snag creation) on 300+ acres at 12 sites in Oregon, Washington, and British Columbia; bird monitoring and research at more than 100 sites in California, Oregon and Washington, and inventories at numerous sites for the endangered Golden-cheeked Warbler in Latin America; and extensive education and outreach activities in both North and Latin America including workshops, training, community and school presentations, and production of several booklets.

and altered by efforts to minimize the potential for wild- Willamette Valley ecoregion, approximately 98% of the 9 fire by reducing fuels loads. remaining oak habitat is on private lands. In the Klam- ath Mountains ecoregion, where oak habitats extend into Fire suppression since European settlement has drastically montane areas with more public land ownership, approxi- altered the structure of oak habitats, the most pronounced mately 65% of the oak habitat is on private land. Thus, being the reduction in open savannah habitats which were 3 habitat protection and restoration to ensure healthy popu- much more common than today. Historic oak savannahs lations of bird species is heavily dependent on conserva- and open-canopy woodlands have become dense forests, tion on private lands. both oak and mixed oak-conifer forests, with higher tree densities in both the overstory and understory.11,12 Fire suppression also has resulted in a more extensive shrub Ecoregions and Oak Habitats understory, and an abundance of nonnative plants in the Ecoregions are relatively large areas with similar assem- 12 herbaceous ground cover. blages of natural communities defined by characteristics There has been a lack of recruitment of new oaks in many such as climate, geology, and vegetation. There are five areas due to a variety of factors. These include fire suppres- ecoregions in the Pacific Northwest where oak habitats sion strategies which thwart oak regeneration by sprout- and their associated bird species are an important com- ing which is stimulated by fire,4,11 reduced acorn produc- ponent of regional biodiversity (Figure 1). Within some tion associated with the reduction of older oak trees, and of these ecoregions there are several discreet sub-regions overgrazing by livestock and/or native ungulates. The con- based on geography and/or ecological differences. sequence is the inability of a sufficient number of seed- lings to become young trees and ultimately replace the Georgia Depression dying older trees. Oak habitats of the Georgia Depression ecoregion, at the Remaining oak habitats tend to be small and disconnect- northern end of oak distribution in the Pacific Northwest, ed, and conservation efforts are problematic because most occur mostly on southeastern Vancouver Island and the Gulf Islands, and at a few locations in the Fraser River of the land ownership is private. In the Puget Lowlands 13 ecoregion, approximately 60% of the oak habitat is on pri- Valley on the mainland of British Columbia. On Van- vate land, and nearly all the public oak habitat is at one site, couver Island and the Gulf Islands, oak habitats mostly Joint Base Lewis McChord Military Installation.7 In the occur in the rain shadow that results in dry summers and

Oak Bird Guide • 7 shallow soils.14 Site-specific characteristics include either a multi-stemmed growth form that functions like chapar- deep-soil parklands where wildfires maintained their exis- ral shrubs. Within the Klamath Mountain ecoregion, two tence over conifer trees, or well-drained soils on south and sub-regions are recognized, the Umpqua Valley and the west-facing slopes with exposed bedrock. Rogue Basin. The latter is referred to as basin rather than valley because oak distribution extends into much higher Puget Lowlands elevations outside the valley. Oak habitats of the Puget Lowlands ecoregion in Wash- ington occur primarily in well-drained gravely soils that East-Slope Cascades are the result of glacial history.2 After glacial retreat, oak Oak habitats of the East-slope Cascades ecoregion occur habitats may have been maintained first by harsh condi- primarily in central and south-central Washington, tions, then by natural fires, and finally by fires set by na- north-central Oregon, and in the Klamath Basin of tive people to ensure a continuing supply of food from south-central Oregon in the rain shadow of the Cascade these systems.15 The current distribution of oak habitats Mountains, often along streams and adjacent slopes is primarily in the south Puget Lowlands sub-region and in canyons associated with major rivers. They occupy a mostly on Joint Base Lewis McChord Military Instal- transition zone between conifer forests and shrub-steppe, lation. Oak habitats of the north Puget Lowlands sub- often being co-dominant with ponderosa pine.16 These region occur primarily on San Juan Island. These habitats drought-prone conditions and steep slopes often result have more similarities to those of the Georgia Depression in less shrub understory than oak habitats west of the ecoregion than the south Puget Lowlands sub-region. Cascade Mountains.

Willamette Valley Oak Habitat Types Oak habitats in the lowlands of the Willamette Valley We recognize four oak-dominant habitat types (where ecoregion are characterized by deep and productive soils oak trees typically comprise > 90% of the canopy) based resulting in oak trees that reach their greatest physical on the amount of canopy cover. These include Oak Savan- stature in the Pacific Northwest.5 This is especially true nah, Oak Woodland Open, Oak Woodland Closed, and in the central and southern Willamette Valley where Oak Forest. There are several other habitat types where there are large areas of oak habitat. In the foothills of oak is co-dominant with other tree species or types (Oak/ the Willamette Valley, oak habitats tend to occur in drier Fir, Oak/Hardwood, Oak/Pine) or growth forms (Oak/ and less productive soils on south and west-facing slopes, Chaparral). We also consider Riparian Oak as a unique especially in the western Willamette Valley in the rain habitat type, although its canopy cover or tree species/ shadow of the Coast Range mountains. Oak habitats in growth form characteristics are consistent with one of the the northern Willamette Valley are most prevalent in other oak habitat types. the Lower Columbia River sub-region which includes the metropolitan area around Portland, Oregon and Oak Savannah Vancouver, Washington. Oak Savannah habitats are grasslands with scattered oak Klamath Mountains trees and an open canopy (<25% cover) with approximately 1-5 large trees or 1-10 younger trees per acre. Oak trees Oak habitats of the Klamath Mountains ecoregion in in savannahs are “open-grown” (i.e., without nearby com- southwest Oregon are the most ecologically diverse oak petition for resources), which at maturity results in large habitats in the Pacific Northwest. Here, the occurrence mushroom-shaped trees with well-developed limbs and of multiple oak tree species represents the convergence canopies. Historically, the understory was typically domi- of California and Pacific Northwest oak communities.11 nated by a ground cover of grasses and forbs with < 10% Oaks occur from the deep clay soils of the lowland valleys, shrub cover. Under current conditions of fire suppression into the drought-prone environments of the foothills, and associated habitat degradation, the understory may and also in the higher precipitation montane environ- include significantly more shrub and small tree cover de- ments. Oak/chaparral habitats, where shrub cover domi- pending on land use and management. Characteristic bird nates, also are a prominent feature of these foothill and species include Lazuli Bunting and Western Bluebird. montane oak habitats. In many of the dry, south-facing slopes, oak trees often occur as short, shrub-layer trees, or

8 • Oak Bird Guide Oak Woodland Open Oak Forest Oak Woodland Open habitats are characterized by a rela- Oak Forest habitats are characterized by a nearly closed tively open canopy (25-50% cover) with approximately canopy (greatner than 75% cover) with typically >30 5-10 large trees or 10-20 younger trees per acre. Oak trees large trees or >40 younger trees per acre. Oak trees in a in open oak woodlands are often a mixture of open-grown dense oak forest compete for resources and are almost ex- trees and columnar shaped trees with limited lower branch clusively columnar in shape with limited branching and and foliage development. The understory was historically crown foliage volume. The sub-canopy and understory can dominated by herbaceous ground cover with variable be devoid of woody vegetation where there is a lack of shrub cover <30% depending on site conditions. Under sunlight reaching the forest floor. Alternatively, in moist, current conditions of fire suppression and associated habi- productive soils, the sub-canopy and understory can be tat degradation, the understory may include significantly densely vegetated with shade tolerant shrub and tree spe- more shrub and small tree cover in the absence of man- cies. Characteristic bird species include Nashville Warbler agement or disturbance. Alternatively, the understory may in the dense understory and Black-headed Grosbeak in include limited or no shrub cover where management the canopy and sub-canopy. is occurring (e.g., grazing, mowing). Characteristic bird species include Chipping Sparrow in the understory and

Western Wood-pewee in the canopy. Bob Altman

Oak/Pine habitat, such as this area in the East-slope Cascades, typically hosts species such as Lewis’s Woodpecker and Western Tanager.

Bob Altman Oak/Pine Mix of Oak Woodland Open and Closed in the Umpqua Valley. Characteristic bird species include Black-capped Chickadee, Cassin’s Vireo, and Western Wood-pewee Oak/Pine habitats are typically woodlands or savannahs characterized by the co-dominance of oak and ponderosa Oak Woodland Closed pine. These habitats predominantly occur in the east-slope Oak Woodland Closed habitats are characterized by a rela- Cascades ecoregion, and to a lesser extent in the Klam- tively closed canopy (50-75% cover) with approximately ath Mountains ecoregion at relatively drier sites, often on 10-30 large trees or 20-40 younger trees per acre. Oak trees moderate to steep slopes in canyons and foothills or on in closed oak woodlands are mostly columnar shaped with plateaus.17 The understory may include pockets of shrubs, limited lower branch and foliage development. The under- but is more typically dominated by grasses and forbs. story was historically dominated by herbaceous ground Characteristic bird species include Lewis’s Woodpecker cover with variable shrub cover <30% depending on site in savannah habitats and Western Tanager in woodland conditions. Under current conditions of fire suppression and forest habitats. and associated habitat degradation, the understory may include some patches of shrub and small tree cover in forest Oak/Fir canopy openings. Characteristic bird species include Purple Oak/Fir habitats are typically closed woodland or forests Finch and White-breasted Nuthatch (subspecies). where there is a relatively equal representation of oak and Douglas-fir in the canopy. This may be a natural community type which occurred primarily in the foothill elevational

Oak Bird Guide • 9 transition into Douglas-fir forests, or where site-specific Oak/Chaparral conditions (e.g., north aspects, moister soil types) were Oak/Chaparral is a shrub-dominated habitat type (often present at the interface with oak habitats. However, the >50% shrub cover) that includes an open canopy of oak most common manifestation of this co-dominance today trees with scattered grassy openings amid dense patches is the result of the encroachment of Douglas-fir as a result of shrubs, in particular evergreen shrubs such as ceano- of fire suppression. There is often some representation of thus and manzanita.1 Oak trees tend to be relatively short dying or dead oak trees in the canopy or sub-canopy as a in stature and often take on a shrub-form growth in result of the competition and over-topping of Douglas- the driest sites. Oak/Chaparral occurs nearly exclusively fir. The understory is typically limited because ofthe in the Rogue Basin and Umpqua Valley sub-regions of closed canopy, but shade-tolerant conifer tree species the Klamath Mountains ecoregion as valley chaparral or (e.g., Douglas-fir, grand fir) are often a component of the montane chaparral. Characteristic bird species include sub-canopy and shrub layers. Characteristic bird species Blue-gray Gnatcatcher and California Towhee. include Black-throated Gray Warbler and Cassin’s Vireo. Riparian Oak Oak/Hardwood Riparian Oak habitats are located adjacent to water bodies Oak/Hardwood habitats are typically closed woodland and can be further defined by any of the other habitat or forests characterized by the co-dominance of oak with types. The main difference is that because of the higher other hardwood species such as madrone, big leaf maple, productivity of riparian soils, Riparian Oak habitats tend or Oregon ash. The former is characteristic of dry sites, to support denser shrub and sub-canopy cover, and often and the latter two of wetter sites such as riparian. The more tree diversity in the canopy, although pure oak in understory is variable in extent - typically limited in both riparian sites is not uncommon. It occurs in all ecoregions, open-grown conditions where tree branching occupies but is most prevalent in the Puget Lowlands and much of the space, or in closed canopies where lack of Willamette Valley. Bird species composition in riparian sunlight limits development; but more robust in the wetter oak is similar to other oak-dominant or co-dominant sites, which support shrub and sapling tree development. types. However, because vegetation volume is high, there This habitat type occurs throughout the region, but is may be a greater species diversity and/or higher densities most prominent in the Klamath Mountains ecoregion. of insectivores and foliage-gleaning birds than occur Characteristic bird species include Hutton’s Vireo and in non-riparian oak sites. Characteristic bird species Black-capped Chickadee. include Black-headed Grosbeak, Bushtit, and Downy Woodpecker. Bob Altman Bob Altman

Oak/Chaparral habitat in the Rogue Basin. Birds characteristic of this habitat type Riparian Oak habitat in the Puget Lowlands. Characteristic birds species include Black- include Blue-gray Gnatcatcher and California Towhee. headed Grosbeak, Bushtit, and Downy Woodpecker.

10 • Oak Bird Guide The Rogue Basin and Oak Bird-Habitat Associations:There are a few unique features about oak habitats in the Rogue Basin that make it challenging to provide a single Pacific Northwest regional characterization for a bird species relationship to habitat types and conditions. In fact, several species show the op- posite habitat associations in the Rogue Basin than elsewhere in the region. For example, species such as Bushtit and Lesser Goldfinch are highly associated with oak savannah in the Rogue, but elsewhere are least associated with oak savannah. Species that typically show this difference are shrub/understory spe-

cies, and the reason appears to be that the understory of oak savannah in most Jaime Stephens places in the region is open with limited shrub cover, but in the Rogue Basin the understory is often chaparral vegetation which results in a relatively dense shrub layer. Thus, shrub-associated species in the Rogue Basin often reach high densities in oak savannah as classified by canopy cover. Another issue is that in many places in the Rogue Basin, oak trees do not grow as tall as elsewhere in the region, and there is less vertical structural layering of vegetation. In these cases, a sub-canopy layer is often absent, and the canopy and shrub layer are compressed closer together and become less distinguishable. Species such as Purple Finch and Downy Woodpecker, which are canopy or sub-canopy associated elsewhere in the region, show associations with the shrub layer in the Rogue Basin because the tops of shrubs in chaparral become part of the canopy of the habitat. Further, species such as Blue-gray Gnatcatcher and Lesser Goldfinch are associated with both the savannah and forest ends of the canopy gradient in the Rogue Basin, because both can contain a dense shrub layer – chaparral in savannah and a dense forest canopy where the site is dominated by short-statured, multi-stemmed oaks that Owen Deutsch function like shrubs. Lesser Goldfinch

Oaks and Birds Amid the vast landscape of Pacific Northwest coniferous forests, oak habitats support a unique avifanua with a high degree of habitat specialization.18 Bird species composition, especially in the Klamath Mountains ecoregion, is in part a northern extension of bird communities of the dry lowlands and foothill oak habitats of central and northern California.2 Despite the diversity of oak habitat types and conditions across the region, there is a relatively similar bird community characterized by a disproportionate number of cavity nesters, resident species, foliage gleaners, and species associated with habitat edges. There are several features of oak trees and associated oak habitats that support the dominance of bird species associated with

these features. Bob Altman Large, “open-grown” oak trees are especially important for bird species such as Western Large Trees Scrub-jay, White-breasted Nuthatch, and Western Bluebird. Mature, large-diameter trees may be the most important such as Hutton’s Vireos and House Wrens. The White- structural element for birds in oak habitats. Large, mature breasted Nuthatch is particularly adapted to gleaning in- trees produce more acorns and have disproportionately sects from the deeply-fissured bark that only occurs on more cavities that are used as roosts and nest sites by nu- large, mature oaks. The berries of the oak mistletoe, found merous species of birds. Older oak trees support a great most commonly in mature oak trees, provide an important diversity of epiphytic plants (lichens and bryophytes) and non-breeding season food resource for Western Bluebirds invertebrates, which offer a corresponding richness of in- outside the breeding season. sect resources available to birds that forage on branches

Oak Bird Guide • 11 Acorns The production of acorns (often referred to as “mast”) is an important feature of oak trees for many bird species. Acorns have a high caloric content and can be an important food resource for species such as Band-tailed Pigeon and Lewis’s Woodpecker during fall and winter when

Greg Homel, Natural Elements Productions Natural Greg Homel, other food resources are scarce. Bird species that cache acorns in the ground such as Western Scrub-jay, and species that drop acorns in transit to cache them in trees such as Acorn Woodpecker and Oak Titmouse, act as seed dispersers for future oak trees. Annual acorn production is highly variable, and few bird species can risk being entirely dependent on acorns. However, good acorn crop years can boost survival and reproduction rates, permitting some bird populations to attain greater densities than would be possible without this resource. Likewise, reduced acorn production as a result of loss or compromised vitality of acorn-producing trees, can negatively affect populations of those same bird species in the long-term.

Dead Wood/Cavities The availability of large-diameter standing dead trees Acorn Woodpeckers act as seed dispersers for future oak trees. (i.e., snags) or dead portions of otherwise live trees is the most limiting factor to populations of cavity-nesting

Bob Altman birds, which as a group comprise approximately 25-30% of the breeding bird species composition in oak habitats, but often more than 50% of the individuals.19 Oak trees support significantly more cavities than conifer 20trees. Further, like many hardwood species, oak trees are better able to compartmentalize injuries and insect damage than conifers, thus providing significant dead wood habitat in an otherwise live tree for primary cavity-excavators such as Lewis’s and Acorn Woodpeckers. In fact, most decaying wood available to birds in oak habitats exists in dead branches of living oak trees.20 As large branches fall off live, mature oaks, pockets of decaying wood become future cavities for secondary cavity-nesting species such as Ash-throated Flycatcher and Black-capped Chickadee. Lastly, arthropods that dwell in decaying wood such as carpenter ants, termites, and beetle larvae are a primary food source for many bird species.

Tree Structure One of the most characteristic features and important habitat components of open-grown oak trees is their mushroom-shape architecture with extensive branching and foliage down to the ground. This branching provides Cavities in old, decaying oak limbs provide nesting habitat for species such as Ash- cover from weather and predators, and extensive foliage throated Flycatcher and Black-capped Chickadee.

12 • Oak Bird Guide development and surface area for foraging and nesting

for birds such as Black-throated Gray Warbler, Blue-gray Bob Altman Gnatcatcher, and Purple Finch. Open-grown oak tree structural development also includes the presence of large lateral branches that provide unique perching opportunities for large birds requiring flatter surfaces such as Turkey Vulture and Wood Duck.

Shrubs Shrubs historically occurred in scattered patches where they escaped fires or in more productive microclimates, and were not as characteristically important as the afore- mentioned features. The major exception to this is Oak/ Chaparral habitats of the Klamath Mountains ecoregion Patch Size and Edge Habitat: Patch size, connectivity, of southwestern Oregon, where shrubs are the dominant and the negative consequences of habitat fragmentation habitat feature. Typical shrub species throughout oak are familiar themes in landbird conservation. However, habitats include snowberry, poison oak, California hazel, these factors appear to be relatively unimportant to most and ocean spray, with ceanothus and manzanita promi- oak-associated bird species. This is likely due to the eco- nent in the Klamath Mountains ecoregion. The presence logical evolution and maintenance of the oak ecosystems of shrubs adds another stratum to the vertical structure in which these species evolved. A combination of the of oak habitats that can increase foraging and nesting vagaries of the different fire intensities and extent that opportunities for bird species such as Bushtit and Nash- maintained these systems, along with the specializations ville Warbler. Shrubs also provide a substrate for insect of oak trees to fine-scaled issues of soil type, aspect, hatches, providing aerial insects for species such as Ash- moisture, and microclimate etc., likely resulted in a landscape mosaic of naturally fragmented and variable-sized throated Flycatcher and Western Wood-pewee. A dense, oak patches with a significant amount of edge habitat. shrub understory supports species such as Bewick’s Wren Thus, the habitat preferences exhibited today by many and Spotted Towhee that are not strongly associated with oak-associated bird species are a reflection of these his- oak trees, and are common species in many other habitats toric conditions dominated by savannah and edges. This dominated by a shrub layer. However, the expansive shrub includes oak savannah species such as Lazuli Bunting, development that has occurred in many oak habitats from Lewis’s Woodpecker, and Western Bluebird, and edge fire suppression and other factors has resulted in the loss species such as Ash-throated Flycatcher, Slender-billed and degradation of the herbaceous-dominated understory White-breasted Nuthatch, Western Scrub-jay, and of oak savannah and open oak woodland habitats.5 In Western Wood-pewee. However, it should be noted that these instances reduction of shrub cover is often consid- some oak-associated bird species do show some asso- ered a management goal. ciation with larger patch sizes including Black-throated Gray Warbler, Hutton’s Vireo, and Purple Finch. Bob Altman Bill Hubick

Purple Finch

Oak Savannah invaded by Himalayan blackberry in the Umpqua Valley. The change has likely moved it from Chipping Sparrow and Western Bluebird habitat to Lazuli Bunting habitat, although the dense blackberry in the upper left has probably exceeded suitability for Lazuli Bunting.

Oak Bird Guide • 13 Table 1. Summary of breeding season habitat relationships of oak-associated bird species in the Pacific Northwest

Primary Structural Layer1 Species (Subspecies) Canopy/ Shrub/ Ground/ Cavity Edges2 Patch Sub-canopy Midstory Shrub Nester Size3 Obligate or Near-Obligate Acorn Woodpecker X X Ash-throated Flycatcher X X X Blue-gray Gnatcatcher X California Towhee X Oak Titmouse X X White-breasted Nuthatch X X X Highly Associated Bewick’s Wren X X Black-capped Chickadee X X Black-headed Grosbeak X Black-throated Gray Warbler X X Bushtit X X Cassin’s Vireo X Chipping Sparrow X Downy Woodpecker X X House Wren X X Hutton’s Vireo X X Lazuli Bunting X Lesser Goldfinch X Lewis’s Woodpecker X X Nashville Warbler X Purple Finch X X Spotted Towhee X Western Bluebird X X Western Scrub-jay X Western Tanager X X Western Wood-pewee X X Oak Savannah/Grassland Associates American Kestrel X Lark Sparrow X Vesper Sparrow X Western Kingbird X Western Meadowlark X

1 X = The structural layer where the species most regularly occurs (only one per species). We recognize that some species use multiple layers, but wanted to characterize the predominant one. Some examples of species using multiple layers include Nashville Warbler, which nests on the ground but is most associated with the shrub/midstory layer, and Chipping Sparrow, which may sing from the canopy/sub-canopy, but forages on the ground and most often nests in the shrub layer. Alternatively, no layer is indicated as primary for Lesser Goldfinch and Western Scrub-jay which use all three categories similarly, and are most characterized by their association with the edges. 2 Many species occur on edges of habitats, but edge species as recognized here are those that are rarely found in the interior of the habitat type during the breeding season, and use edge habitats for all their nesting and foraging activities. 3 Species reported to have requirements for larger patch sizes based on two studies that assessed this parameter.22, 23 Only Black-throated Gray Warbler was reported in both studies.

14 • Oak Bird Guide Tom Grey Tom

Western Bluebirds; female on left, male on right. Oak Bird Species Our list of oak-associated bird species is based on three Oak Habitat Conservation for Res- 1,18,21 previous assessments with several modifications based ident and Cavity-Nesting Birds: Greg Lavaty on more recent data and analyses. Obligate or near-obli- Among the 26 species we consider gate species are those with > 75% of their historic or cur- to be most highly associated with rent population in the Pacific Northwest in oak habitats oak habitats in the Pacific North- (Table 1). It is noteworthy that none of these six species west, 10 (39%) are cavity-nesters and are distributed throughout the region, but they all occur in 12 (46%) are resident species. These the Rogue Basin sub-region and southern portion of the numbers are the highest for these East-slope Cascades ecoregion. Four of the six obligate categories in any habitat type in the Pacific Northwest. This provides or near-obligate species (67%) are resident cavity-nesters some relatively clear direction for a primarily associated with canopy or sub-canopy habitats. Downy Woodpecker primary bird conservation strategy Highly associated species are those that are abundant in in oak habitats in the Pacific Northwest – the protection some other habitat(s), but reach some of their highest of mature oak trees and habitat management and resto- densities in oak habitats (Table 1). The majority of oak- ration to promote the development of mature trees and associated bird species fit this description. Among these their associated characteristics. Natural cavities are dis- 20 species, six (30%) are cavity-nesters and eight (40%) proportionately more available in mature trees, especially are resident species. open-grown trees, and year-round habitat for resident and cavity-nesting birds requires suitable conditions Lastly, we recognize five additional species that are pri- and adequate resources, both of which are more avail- marily grassland species, but regularly occur in oak savan- able with mature trees. This includes cavity roosting sites, nah (Table 1). There also are a few species not included acorns as food for some species (e.g., Acorn Woodpecker, in Table 1 that can be regularly found in oak habitats, Lewis’s Woodpecker), and non-acorn foraging resources but tend to have broader habitats preferences and occur such as invertebrates living in lichens and bryophytes, in higher densities in other habitat types (e.g., Bullock’s arthropods in decaying branches, and mistletoe berries Oriole in riparian, Wrentit in early-successional conifer in canopy branches, all of which are most prevalent in forest, and Band-tailed Pigeon in mixed-conifer forest). mature trees.

Oak Bird Guide • 15 Table 2. Oak-associated bird species designated as being of conservation concern by the primary wildlife natural resource agencies in the Pacific Northwest Species (Subspecies) USFWS 1 ODFW 2 WDFW 3 Acorn Woodpecker W Blue-gray Gnatcatcher K Chipping Sparrow W Vesper Sparrow (Oregon) X KW P Lewis’s Woodpecker K White-breasted Nuthatch W P Western Bluebird W P Western Meadowlark W

1 USFWS = U.S. Fish and Wildlife Service Birds of Conservation Concern in Bird Conservation Region 524 2 ODFW = Oregon Department of Fish and Wildlife Species of Greatest Conservation Need25 (W = Willamette Valley ecoregion; K = Klamath Mountains ecoregion) 3 WDFW = Washington Department of Fish and Wildlife Species of Greatest Conservation Need26 (P = Puget Lowlands ecoregion) Bob Altman James Livaudais

White-breasted Nuthatch

Oak Bird-Habitat Relationships Summaries: The Priority and Focal Species habitat associations and finer-scaled habitat relation- Many bird species associated with oak habitats are of ships of our 26 oak-associated bird species are presented conservation concern due to declines in populations, local in several ways. Relationships to habitat structure and extirpations, or close associations with declining habitat special habitat features are indicated in Table 1. The degree of occurrence of each species across the gradient types (e.g., oak savannah) (Table 2). This includes three of oak habitat types is depicted in Figure 2. The habitat cavity-nesting breeding species with local or regional condition(s) that each species is most associated with extirpations: Lewis’s Woodpecker from western Oregon, is presented in Table 3. Potential population response western Washington, and southwestern British Columbia to typical habitat management and restoration activities since the 1960s; Western Bluebird from southwestern is projected in Tables 4 and 5. Finally, for each species British Columbia and northwestern Washington since the there is a Species Account in Appendix A that provides 1960-1970s, and Slender-billed White-breasted Nuthatch supplementary information on population trends, range, recently extirpated (1990s) from the south Puget Lowlands nesting, and density estimates by ecoregion and habitat of western Washington.18 Further, there are two oak type based on data from a variety of sources listed in savannah ground-nesting species that have experienced Appendix B. local extirpations: Western Meadowlark from southwestern

16 • Oak Bird Guide Lewis’s Woodpecker: Poster Bird for Oak Savannah Conservation

Lewis’s Woodpecker was formerly an uncommon to locally abundant breeding species in oak habitats in all four of the ecoregions of western Oregon and Washington and southwestern British Columbia.18 By the early 1960s it began to disappear as a breeding species starting in the Georgia Depression and San Juan Islands of the north Puget Lowlands. By the early 1970s it was gone as a breeding species in the south Puget Lowlands and Willamette Valley. It maintained a breeding presence in the Klamath Mountains through the 1980s, but is currently not known to breed anywhere in these ecoregions. This regional extirpation mirrors the loss and degradation of oak habitats in the region, particularly the extensive areas of oak savannah dominated by large trees which is the required habitat for this cavity-nesting bird. Bringing back breeding populations of Lewis’s Woodpecker, and the expansive oak savannahs they depended on, is a driving vision for bird conservationists in oak habitats of the Pacific Northwest. John White John

Oak Bird Guide • 17 Figure 2. Degree of Occurrence of Bird Species Across the Gradient of Prairie-Oak Habitat Types

Wet Prairie Upland Prairie Oak Savanna Oak Woodland Open Oak Woodland Closed Oak Forest Mixed Oak-Conifer

Northern Harrier

Short-eared Owl (1) Species occurrence/density is dependent on suitable cavities for nest sites (2) Species occurrence/density is dependent on shrub cover Horned Lark (Streaked) (3) Species occurrence/density is dependent on low-statured grasses in the ground cover Savannah Sparrow (4) Species occurrence/density may be dependent on larger patches of habitat (5) Species occurrence/density may be dependent on habitat edges or openings Western Meadowlark Species occurrence Grasshopper Sparrow Species density usually highest Lark Sparrow

Vesper Sparrow (Oregon)

Western Kingbird

American Kestrel (1)

Western Bluebird (1, 3)

Ash-throated Flycatcher (1, 5)

Blue-gray Gnatcatcher (2)

Lazuli Bunting (2)

Lewis’s Woodpecker (1)

California Towhee (2, 3)

Chipping Sparrow (3)

Western Scrub-jay (3, 5)

Spotted Towhee (2)

Lesser Goldfinch (5)

Oak Titmouse (1)

Bewick’s Wren (1,2)

House Wren (1, 2)

Bushtit (2, 4)

Acorn Woodpecker (1)

Black-headed Grosbeak

Western Tanager (5)

Nashville Warbler (2) NOTE: Species occurrence/density as indicated here is a general Black-throated Gray Warbler (4) regional perspective based on canopy cover defining the habitat Purple Finch (4) type. Ecoregional or local variability in occurrence/density can Downy Woodpecker (1) occur, especially based on the more specific habitat conditions described in the legend above. Black-capped Chickadee (1)

Western Wood-pewee (5)

White-breasted Nuthatch (Slender-billed) (1, 5)

Hutton’s Vireo (2, 4)

Cassin’s Vireo

18 • Oak Bird Guide Using Focal Species in Conservation Planning and Implementation: Focal species are typically used as representatives of the desired habitat conditions for conservation. If the desired objective is for an oak savannah or open woodland landscape (e.g., 10-40% canopy cover), useful focal species might be Western Scrub-jay for canopy cover and Chipping Sparrow or Lazuli Bunting for the relationship between understory shrub cover and herbaceous ground cover. In the Rogue Basin of the Klamath Mountains ecoregion, California Towhee could be used to capture the relationship between shrub Chipping Sparrow: Tom Grey Tom Chipping Sparrow: cover and herbaceous ground cover. If the objective is for an oak woodland of 30-70% cover, useful focal species would be White-breasted Nuthatch for tree size, Western Wood-pewee for the more open canopy with edges desired condition, Cassin’s Vireo or Purple Finch for the more closed canopy condition, and House Wren or Hutton’s Vireo for shrub cover in the understory (Nashville Warbler in the Klamath Mountains ecoregion). It is important to recognize that these conditions are not the full habitat requirements for the focal species; the conservation emphasis is on using the focal species to describe the desired habitat conditions, but not to describe the conservation of the species itself.

British Columbia and northwestern Washington in the the desired conditions is likely to encompass the habitat 1970-1980s, and Oregon Vesper Sparrow nearly extirpated requirements of most if not all the other species in the from southwestern British Columbia.18 bird community. Another way of considering important species for conser- Focal species for oak habitats in the Pacific Northwest vation is the concept of focal species.27 These are species were originally identified by the Oregon-Washington that are highly associated with a particular habitat type Partners in Flight initiative (www.orwapif.org) in two or habitat feature and can be used as indicators of that bird conservation plans, Westside Lowlands and Valleys21 habitat condition(s) in conservation planning, implemen- and East-slope Cascades.28 A more extensive assessment tation, and monitoring. The occurrence and/or density of of oak habitat focal species was prepared for use in setting focal species or their associated habitat conditions also population and habitat objectives in oak habitats in the can be used as representative of the conservation of other Pacific Northwest.29 Significant bird and habitat monitor- species associated with the same or similar conditions. The ing in oak habitats over the last few years has resulted in premise is that a site or landscape that meets the habitat new data that provides us with an opportunity to update requirements of a suite of focal species representative of those efforts (Table 3).

Focal Bird Species and Effectiveness Monitoring:By monitoring both birds and vegetation before and after restoration, we can evaluate whether a project has achieved its intended out- come and guide further restoration actions if needed. While, the ultimate metric of the success of the habitat management or restoration actions should be the assessment of the vegeta- tive conditions created to support focal species, the response of focal species provides us with additional understanding of ecological change. The use of a suite of focal species representing a range of the habitat conditions will provide a more robust measure of effectiveness than a single species. The presence or density of a suite of focal bird species can be used as a positive indicator of the “effectiveness or success” of habitat management or restoration activities at a site, but should not be used as the primary metric for effectiveness because of the potential for factors beyond habitat to affect bird species. There are a number of reasons why a bird species may not occur at a site with seemingly appropriate habitat, such as proximity and status of the nearest species populations and the ability of those populations to provide recruitment into

the site, or that our knowledge of the targeted habitat conditions for the species is incomplete Grey Tom Titmouse: Oak or inaccurate. Thus, it is possible that habitat management or restoration can be successful in achieving the desired habitat conditions, but still not support the targeted focal species. While the absence or low density of some focal species might not indicate failure, it should prompt further evaluation of restoration effectiveness and/or species ecology. From a bird conservation perspective, understanding what is limiting populations in restored oak habitat is critical to both inform future restoration and refine our knowledge of the habitat needs of focal species.

Oak Bird Guide • 19 Table 3. Focal species habitat associations by ecoregion/sub-region for oak habitats in the Pacific Northwest

1Although each species is only listed for one habitat category, they may be used as focal species for the same habitat condition in other habitat categories if they are also regularly occurring in those categories. 2Shading indicates the species does not occur or only occurs to a very limited degree as a breeding species in oak habitats in an ecoregion/sub-region, and is not useful as a focal species; X indicates species that are suggested as focal species to be used in planning, implementation, and monitoring because their distribution and density is relatively good throughout the ecoregion/sub-region. X indicates species that could be used as focal species, but their densities are relatively low. If any of the suggested focal species are not present or are only minimally present at a particular site or area, use of other focal species with similar habitat associations may be appropriate.

20 • Oak Bird Guide There are two ways to use bird focal species in the conser- Density Estimates vation of oak habitats. First, the specifics of their repre- Bird density estimates (i.e., number of birds per area) can sentative habitat associations (e.g., canopy cover or shrub be an important tool in bird conservation. Firstly, density cover, tree size) can be used in the planning process to set estimates for a habitat type provides the opportunity to habitat objectives for a site or landscape. Secondly, their calculate an estimate of the population of a species. Sec- occurrence or density can be used as a metric to track pos- ondly, density estimates used in conjunction with other itive progress of management or restoration towards the information on population trends, historic population habitat objectives they represent. Although both of these baselines, or desired populations can be used to set popu- can be done for individual species, the most ecologically lation objectives. Through bird monitoring, a density es- sound approach is to use a suite of focal species whose timate can be readily calculated, which can become the habitat associations capture the range of desired condi- metric used to set the objective or easily converted to a tions at a site or across a landscape. population estimate as the objective. The use of density estimates to calculate population estimates and set population objectives has been done for oak and other habitats in the Puget Lowlands ecoregion.30 Some examples of ecoregional mean density estimates for oak-associated bird species are provided in Table 4. Greg Homel, Natural Elements Productions Natural Greg Homel,

Ash-throated Flycatcher

Oak Bird Guide • 21 Table 4. Ecoregion/sub-region mean density estimates (birds/ha) for oak-associated bird species in oak-dominant habitats in the Pacific Northwest1

Georgia Depression Willamette Valley Rogue Basin Spotted Towhee 1.24 Spotted Towhee 1.20 Spotted Towhee 0.80 Bewick’s Wren 0.66 Black-capped Chickadee 0.55 Lesser Goldfinch 0.70 Chipping Sparrow 0.26 Western Wood-pewee 0.52 Lazuli Bunting 0.68 Western Tanager 0.13 House Wren 0.30 Blue-gray Gnatcatcher 0.51 House Wren 0.11 Bewick’s Wren 0.22 Black-headed Grosbeak 0.43 Black-headed Grosbeak 0.17 Nashville Warbler 0.41 Puget Lowlands Lesser Goldfinch 0.17 Chipping Sparrow 0.36 Spotted Towhee 0.89 White-breasted Nuthatch 0.17 Western Tanager 0.30 Western Wood-pewee 0.60 Purple Finch 0.16 Western Wood-pewee 0.23 Chipping Sparrow 0.42 Lazuli Bunting 0.14 California Towhee 0.22 House Wren 0.41 Western Scrub-jay 0.11 Ash-throated Flycatcher 0.20 Black-capped Chickadee 0.28 Western Tanager 0.11 Bushtit 0.19 Purple Finch 0.28 Black-throated Gray Warbler 0.10 House Wren 0.19 Western Tanager 0.11 Chipping Sparrow 0.10 Oak Titmouse 0.19 Downy Woodpecker 0.10 Purple Finch 0.17 Umpqua Valley White-breasted Nuthatch 0.13 Spotted Towhee 0.75 East-slope Cascades Black-throated Gray Warbler 0.11 Lazuli Bunting 0.54 Chipping Sparrow 0.47 Black-capped Chickadee 0.33 Black-headed Grosbeak Spotted Towhee 0.39 Chipping Sparrow 0.19 Nashville Warbler 0.34 Western Tanager 0.19 Lazuli Bunting 0.25 Western Wood-pewee 0.15 Western Tanager 0.20 Black-headed Grosbeak 0.14 Black-throated Gray Warbler 0.13 House Wren 0.12 Western Wood-pewee 0.10 Lesser Goldfinch 0.10 White-breasted Nuthatch 0.10

1 Only species with density estimates ≥0.10 birds/ ha. are included. Ecoregion/sub-region mean den- Tom Grey Tom sity estimates are derived from an analysis of the data sources listed in Appendix B, which include data from all oak-dominant habitat types and from multiple methods (e.g., fixed and variable radius point counts, spot-mapping). There is inherent variability and uncertainty when combining data from Greg Lavaty different habitat types and multiple methods, but density estimate comparisons among species within an ecoregion/sub-region provides a starting point for identifying relative importance and potential value of species for use in planning or monitoring. Further, since the numbers reflect a singular mean density estimate for an entire ecoregion/sub-region, they are best used in landscape level analyses of multiple sites, rather than as representative of any individual site.

Spotted Towhee

22 • Oak Bird Guide Density estimates also can be used to predict changes in a species population based on habitat management or restoration activities. Knowledge of a species density estimate for both the baseline and projected future habitat type or condition provides an easy method for calculating the corresponding predicted changes in a species population (Tables 5 and 6).

Response to Habitat Management and Restoration Significant oak habitat management and restoration has been and continues to be implemented throughout the region in the last 10-15 years. Detailed information on Bob Altman planning, decision-making, techniques etc. for oak habitat management and restoration is beyond the scope of this 16,31,32,33,34,35 Sub-canopy and Understory document, but is available in numerous sources. Bird species response to habitat management or resto- Herein, we provide some quantitative and qualitative ration that would change sub-canopy, shrub, or ground context for how different oak habitat management and cover were subjectively indicated as positive, negative, or restoration activities might potentially affect bird species neutral (Table 6) based on an understanding of species populations in the short term. We do not do this for ac- associations with these conditions from various studies tivities with long-term objectives such as planting oaks and data sets (Appendices A and B). The sub-canopy and for future habitat or releasing oak trees from competition understory management or restoration examples consid- to encourage “open-growth” and development of lateral ered here include: branching. • thinning from below of sub-canopy oak trees, conifer Canopy trees, or invasive trees (e.g., hawthorne) that would reduce Density data (Appendices A and B) were used to predict midstory structural diversity. the potential change in population from habitat manage- • removal of shrub cover that would open up the under- ment or restoration activities that would change the habi- story and provide more herbaceous openings. tat type based on canopy cover (Table 5). We only consid- • herbaceous height control through poor soil productivity ered substantial changes in type where the habitat would (e.g., gravelly soils, shallow soils on dry sites) or manage- move at least two habitat types to avoid trying to distin- ment such as mowing or grazing outside the nesting season. guish between more subtle changes. The canopy management or restoration examples considered here include:

• oak thinning that would reduce canopy cover and change White John Oak Forest to Oak Woodland Open or Oak Savannah. • oak thinning that would reduce canopy cover and change Oak Woodland Closed to Oak Savannah. • removal of conifers, especially Douglas-fir to “release” oaks that would reduce canopy cover and change Oak/Fir forest to Oak Woodland Closed, Oak Woodland Open, or Oak Savannah.

Western Tanager

Oak Bird Guide • 23 Table 5. Projected potential bird species short-term population response to canopy management in oak habitats1

Canopy Oak Thinning2 Canopy Douglas-fir Removal2 Species       OF OWO OF OS OWC OS ODF OWC ODF OWO ODF OS Acorn Woodpecker o o o o o o Ash-throated Flycatcher ++++ ++++ ++++ + ++++ ++++ Bewick’s Wren o o o ++++ ++++ ++++ Black-capped Chickadee ------++ ++ - Black-headed Grosbeak ------Black-throated Gray Warbler ------Blue-gray Gnatcatcher -- + ++++ +++ ++++ ++++ Bushtit +++ ++++ +++ o +++ ++++ California Towhee ++++ ++++ ++++ +++ +++ ++++ Cassin’s Vireo o ------Chipping Sparrow ++++ ++++ + + ++++ ++++ Downy Woodpecker ------o o o House Wren + ++ + ++++ ++++ ++++ Hutton’s Vireo - --- o o o --- Lazuli Bunting ++++ ++++ ++ ++ ++++ ++++ Lesser Goldfinch ++ ++++ ++++ + ++++ ++++ Nashville Warbler + ------Oak Titmouse ++++ ++++ + +++ ++++ ++++ Purple Finch o o o + o + Spotted Towhee o o o o o o White-breasted Nuthatch - - o +++ ++++ +++ Western Bluebird o o o o o o Western Scrub-jay + + +++ o +++ +++ Western Tanager + - -- o o ---- Western Wood-pewee o -- -- ++++ ++++ +

1Projected potential bird species short-term population response is based on changes in mean regional density estimates. Potential is dependent on many factors beyond the actual habitat management or restoration, thus is not the expected response. Further, local or ecoregional variability in species density estimates may result in different projections of change than the region-wide projections presented below. Thus, use of this table should provide an initial projection of bird population response based on regional data that should be further assessed with local data. 2 The degree of population response as indicated by the number of positive (+) or negative (-) signs is used to distinguish between species with low, moderate, or high densities where similar percent changes in density can result in different degrees of population response. For example, an increase of 100% or doubling of the population from a density of 1.0 birds/ha to 2.0 birds/ha results in one new bird, whereas a 100% increase or doubling of the population from a density of 3.0 birds/ha to 6.0 birds/ha results in three new birds; hence,

a greater increase in the local population. Thus, based on the criteria below, more signs indicate the potential for greater change in the Elements Productions Natural Greg Homel, actual population. + or - = <100% change in density and <.10 change in actual density ++ or -- = <100% change in density and >.10 change in actual density +++ or --- = >100% change in density and <.10 change in actual density ++++ or ---- = >100% change in density and >.10 change in actual density o = same density or <25% change in density or ≤.02 change in actual density OS = 1-25% canopy cover; OWO = 25-50% canopy cover; OWC = 50-75% canopy cover; OF = 75-100% canopy cover; ODF = Oak/Fir

Lazuli Bunting

24 • Oak Bird Guide Table 6. Projected potential bird species short-term population response to sub-canopy and understory management in oak habitats1

2 Species Sub-canopy Shrub Cover Reduction Herbaceous Tree Height 2 Closed to Closed to Semi-Open 2 Thinning Semi-Open Open to Open Control

Acorn Woodpecker + o o o o Ash-throated Flycatcher + o o o o Bewick’s Wren o - - - o Black-capped Chickadee - o - - o Black-headed Grosbeak - o o o o Black-throated Gray Warbler - o o o o Blue-gray Gnatcatcher o o - - o Bushtit - o - - o California Towhee o o - - + Cassin’s Vireo - o o o o Chipping Sparrow o + + + + Downy Woodpecker - o o o o House Wren o o - - o Hutton’s Vireo - o - - o Lazuli Bunting o o - - - Lesser Goldfinch o o o + - Nashville Warbler - - - - o Oak Titmouse o o - - o Purple Finch - o o o o Spotted Towhee o o o - - White-breasted Nuthatch + o o o o Western Bluebird o + + + + Western Scrub-jay + o + + + Western Tanager + o o o o Western Wood-pewee + o o o o

1 Projected potential bird species short-term population response is based on subjective assessments of species habitat relationships and knowledge of the effects on vegetation from the activities. Potential is dependent on many factors beyond the actual habitat management or restoration, thus is not the expected response. Thus, use of this table should provide an initial projection of bird population response that needs to be further assessed with local data. 2 Projected potential population response is positive (+), negative (-), or neutral (o). An attempt was made to provide a singular response to each action based on the most likely scenario using the following parameters: Sub-canopy tree thinning from > 20% cover to <20% cover; Shrub cover reduction amounts, Closed = >60%; Semi-open = 20-60%; Open = <20%; and herbaceous height control, maintaining herbaceous layer <0.5 meters high from normal growth exceeding that. However, species potential response is invariability more complex that a simple positive, negative or neutral and dependent on a variety of factors. Neutral (o) was the default response when there was not a relatively clear relationship and much uncertainly existed.

Oak Bird Guide • 25 Literature Cited 12. Fuchs, M. A. 2001. Towards a recovery strategy for Garry 1. Altman, B., M. Hayes, S. Janes, and R. Forbes. 2001. Wildlife oak and associated ecosystems in Canada: ecological assessment communities of westside grassland and chaparral habitats. Pp. and literature review. Technical report GBEI/EC-00-030. En- 261-291 in D. Johnson and T. O’Neil (editors), Wildlife- vironment Canada, Canada Wildlife Service, Pacific and Yukon habitat relationships in Oregon and Washington. Oregon State Region. University Press, Corvallis. 13. Erickson, W. R. 1996. Classification and interpretation of 2. Ewing. K. 1997. Management and restoration of south Puget Garry Oak plant community communities and ecosystems in Sound prairies and woodlands. Pp. 3-9 in P. Dunn and K. Ewing southwestern British Columbia. M.Sc. Thesis, University of Vic- (editors), Ecology and conservation of the south Puget Sound toria, British Columbia. prairie landscape. The Nature Conservancy of Washington, Seattle. 14. Roemer, H. 1993. Vegetation and ecology of Garry Oak woodlands. Pp. 19-24 in R. J. Hebda and F. Aitkens (editors), 3. Franklin, J. F. and C. T. Dyrness. 1973. Natural vegetation of Proceedings of Garry Oak-Meadow Colloquium, University of Oregon and Washington. U. S. Forest Service General Techni- Victoria, Victoria, British Columbia. cal Report, PNW-GTR-8. 15. Norton, H. H. 1979. The association between anthropogen- 4. Agee, J. K. 1993. Fire ecology of Pacific Northwest forests. ic prairies and important food plants in western Washington. Washington, D.C. Island Press. Northwest Anthropological Research Notes 13:175-200.

5.Thilenius, J. F. 1968. The Quercus garryana forests of 16. Larson, E. M. and J. T. Morgan. 1998. Management the Willamette Valley, Oregon. Ecology 49: 1124-1133. recommendations for Washington’s priority habitats: Oregon white oak woodlands. Washington Department of Fish and 6. Lea, T. 2002. Historical Garry oak ecosystems of greater Vic- Wildlife, Olympia. 37 pp. toria and Saanich Peninsula – a 1:20,000 Map. Pp. 24-27 in P. J. Burton (editor), Garry Oak Ecosystem Restoration: Progress 17. Crawford, R. C. and J. Kagan. 2001. Ponderosa pine forest and Prognosis. Proceedings of the third annual meeting of the and woodland (includes eastside oaks). Pp. 35-37 in D. H. John- British Columbia chapter of the Society for Ecological Restora- son and T. A. O’Neil (managing directors), Wildlife-habitat re- tion, April 27-28, 2002. University of Victoria, British Colum- lationships in Oregon and Washington. Oregon State Univer- bia. sity Press, Corvallis. 736 pp.

7. Chappell, C. B., M. S. MohnGee, B. Stephens, R. Crawford, 18. Altman, B. 2011. Historical and current distributions and and S. Farone. 2000. Distribution and decline of native grasslands populations of prairie-oak birds in the Pacific Northwest. and oak woodlands in the Puget Lowland and Willamette Northwest Science 85:194-222. Valley Ecoregions, Washington. Washington Natural Heritage Program, Washington Department of Natural Resources, 19. Noon, B. R., P. N. Manley, and R. A. Wilson. 1988. Silvi- Olympia, Washington. cultural options in managed oak woodlands to benefit breeding birds. Department of Wildlife, Humboldt State University un- 8. Public Forestry Foundation. 1995. Forest management strat- published report submitted to California Department of For- egy for the Fort Lewis Military Reservation. Prepared for U. S. estry. 101 pp. Army I-Corps, Fort Lewis Military Reservation, Environmental and Natural Resources Division, Forestry Branch, and The Na- 20. Gumtow-Farrior, D. L. 1991. Cavity- resources in Oregon ture Conservancy of Washington. Eugene, Oregon. white oak and Douglas-fir stands in the mid-Willamette Valley, Oregon. M.S. Thesis. Oregon State University, Corvallis. 89 pp. 9. Defenders of Wildlife. 1998. Oregon’s Living Landscape. Defenders of Wildlife, West Linn, Oregon. 218 pp. 21. Altman, B. 2000. Conservation strategy for landbirds in the lowlands and valleys of western Oregon and Washington. Ver- 10. Hulse, D. W., J. M. Eilers, K. Freemark, C. Hummons, sion 1.0. American Bird Conservancy and Oregon-Washington and D. White. 2000. Planning alternative future landscapes in Partners in Flight. www.orwapif.org. Oregon: Evaluating effects on water quality and biodiversity. Landscape Journal 19:1-19. 22. Viste-Sparkman, K. 2005. White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette valley, 11. Riegel, G. M., B. G. Smith, and J. F. Franklin. 1992. Oregon. M.S. Thesis, Oregon State University, Corvallis. 96 pp. Foothill oak woodlands of the interior valleys of southwestern Oregon. Northwest Science 66:66-76.

26 • Oak Bird Guide 23. Altman, B. 2008. Ground-truthing habitat-based popula- 35. Hosten, P. E., O. E. Hickman, F. K. Lake, F. A. Lang, and tion estimates for birds in oak habitats in the Northern Pacific D. Vesely. 2006. Oak woodlands and savannah. Pp. 63-96 in D. Rainforest Bird Conservation Region. American Bird Conser- Apostal and M. Sinclair (editors), Restoring the Pacific North- vancy, unpublished report prepared for U. S. Fish and Wildlife west: The Art and Science of Ecological Restoration in Cascadia. Service. 12 pp. Island Press, Washington, D. C.

24. U.S. Fish and Wildlife Service. 2008. Birds of Conservation 36. Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, D. J. Concern, 2008. U. S. Fish and Wildlife Service, Division Ziolkowski, Jr., and W. A. Link. 2011. The North American of Migratory Bird Management, Arlington, Virginia. Breeding Bird Survey, Results and Analysis 1966-2010. Version 85 pp. http:/ www.fws.gov/migratorybirds. 12.07.2011 USGS Patuxent Wildlife Research Center, Laurel, MD. 25. Oregon Department of Fish and Wildlife. 2005. Oregon Conservation Strategy. Oregon Department of Fish and 37. Hagar, J. C. and M. A. Stern. 1997. Avifauna in oak Wildlife, Salem. woodland habitats of the Willamette Valley, Oregon, 1994-1996. Oregon Natural Heritage Program, The Nature Conservancy of 26. Washington Department of Fish and Wildlife. 2005. Oregon unpublished report to U. S. Fish and Wildlife Service, Washington’s Comprehensive Wildlife Conservation Strategy. Portland. 33 pp. Washington Department of Fish and Wildlife, Olympia. http:/ wdfw.wa.gov/conservation/cwcs/. 38. Johnson, E. M. and D. K. Rosenberg. 2006. Granary site- selection by Acorn Woodpeckers in the Willamette Valley, Or- 27. Lambeck, R. J. 1997. Focal species: a multi-species umbrella egon. Northwest Science 80:177-183. for nature conservation. Conservation Biology 11:849-856. 39. Doerge, K. F. 1979. Aspects of the geographic ecology of 28. Altman, B. 2000. Conservation strategy for landbirds of the the acorn woodpecker. M.S. Thesis, Oregon State University, East-slope of the Cascade Mountains of Oregon and Washington. Corvallis, Oregon. Version 1.0. American Bird Conservancy and Oregon- Washington Partners in Flight. www.orwapif.org. 40. Altman, B. and J. Lloyd. 2012. Bird-habitat relationships in oak habitats of western Oregon. American Bird Conservancy 29. Stockenberg, E., B. Altman, M. Green, and J. D. Alexander. and Ecostudies Institute unpublished report. 91 pp. 2008. Using GAP in landbird biological objective setting: process and examples from oak habitats in the Pacific Northwest. 41. Raphael, M. G. 1987. Wildlife-tanoak associations in Doug- The Gap Analysis Bulletin 15:34. las-fir forests of northwestern California. U. S. Forest Service General Technical Report PSW-GTR-100. Pacific Southwest 30. Altman, B. 2010. Habitat and population objectives for land- Forest and Range Experiment Station, Berkeley, California. birds in priority upland and riparian habitats in the Puget lowlands ecoregion. American Bird Conservancy and Pacific Coast Joint 42. Stralberg, D and B. Williams. 2002. Effects of residential Venture. 42 pp. www.pcjv.org/home/implementation/puget.html. development and landscape composition on the breeding birds of Placer County’s foothill oak woodlands. Pp. 341-363 in R. B. 31. Chiller, D. G., D. G. Vesely, and W. I. Dean. 2000. As- Standiford, D. McCreary, and K. L. Purcell (editors), Proceed- sessment of oak woodland resources in BLM’s Eugene District, ings of the 5th Oak Symposium: Oaks in California’s Chang- Lane County, Oregon. U. S. Bureau of Land Management, ing Landscape. U. S. Forest Service General Technical Report Technical Note 406. Eugene, Oregon. 81 pp. PSW-GTR-184.

32. GBA Forestry. 2002. A management strategy for oak 43. Wilson, R. A., P. Manley, and B. R. Noon. 1991. woodlands of Fort Lewis, Washington. Unpublished report Covariance patterns among birds and vegetation in a California prepared for U. S. Army, Fort Lewis Military Installation, oak woodland. Pp. 126-135 in R. B. Standiford (technical Environmental and Natural Resources Division, Forestry coordinator), Proceedings of the symposium on oak woodlands Branch, and The Nature Conservancy of Washington. 47 pp. and hardwood rangeland management. U. S. Forest Service, Pacific Southwest Research Station General Technical Report 33. Campbell, B. H. 2004. Restoring rare native habitats in the PSW-GTR-126. Willamette Valley: a landowner’s guide for restoring oak woodlands, wetlands, prairies, and bottomland hardwood and riparian 44. Manuwal, D. A. 1997. Neotropical bird communities in forests. Defenders of Wildlife, West Linn, Oregon. 123 pp. oak woodlands of south-central Washington. College of Forest Resources, University of Washington, Seattle, unpublished 34. Vesely, D. and G. Tucker. 2004. A landowner’s guide for Final Report to Washington Department of Fish and Wildlife, restoring and managing Oregon white oak habitats. U.S. Bureau Vancouver, and U.S. Fish and Wildlife Service, Portland, of Land Management, Salem, Oregon. Oregon. 123 pp.

Oak Bird Guide • 27 45. Seavey, J. 1997. Nest site selection and nesting success of 53. Richardson, C., and F. W. Sturges. 1964. Bird records from the ash-throated flycatcher in south-central Washington. M.S. southern Oregon. Condor 66:514-515. Thesis, University of Washington, Seattle. 54. Feldman, R. E. 2002. Associations of songbirds with their 46. Manley, P. N. 1988. Resource portioning in an avian guild in habitat in the Garry Oak (Quercus garryana) ecosystem of an oak woodland. M.S. Thesis, Humboldt State University, Victoria, British Columbia, Canada. M.Sc. Thesis, University of California. 122 pp. British Columbia, Vancouver.

47. Alexander, J. D., N. E. Seavy, and P. E. Hosten. 2007. Using 55. Anderson, S. H. 1970. The avifauna composition of Oregon conservation plans and bird monitoring to evaluate ecological ef- white oak stands. Condor 72:417-423. fects of management: an example with fuels reduction activities in southwest Oregon. Forest Ecology and Management 238: 56. Alexander, J. D., J. L. Stephens, and N. E. Seavy. 2008. 375–383. Livestock utilization and bird community composition in mixed- conifer forest and oak woodland in southern Oregon. Northwest 48. Seavy, N. E., J. D. Alexander, and P. E. Hosten. 2008. Bird Science 82:7–17. community composition after mechanical mastication fuel treat- ments in southwest Oregon oak woodland and chaparral. Forest 57. California Partners in Flight. 2002. The oak woodland bird Ecology and Management 256: 774–778. conservation plan: a strategy for protecting and managing oak woodland habitats and associated birds in California. Version 49. Resources Northwest and Pentec Environmental. 1995. 2.0. (S. Zack, lead author). Point Reyes Bird Observatory, Stin- Neotropical migratory bird survey: Fort Lewis Military Reserva- son Beach, CA. http://www.prbo.org/calpif/plans.html. tion. Unpublished final report submitted to U. S. Army Corps of Engineers and Fort Lewis Military Reservation. 58. Manuwal, D. A. 1989. Birds of the riparian and adjacent oak habitats along the Klickitat River, Washington. College of For- 50. Cross, S. P. and J. K. Simmons. 1983. Bird populations of est Resources, University of Washington, Seattle, unpublished the mixed-hardwood forests near Roseburg, Oregon. Oregon Final Report to Washington Department of Fish and Wildlife, Department of Fish and Wildlife, Nongame Wildlife Program Vancouver and U. S. Forest Service, Hood River, Oregon. 70 Technical Report 82-2-05. pp.

51. Rolph, D. N. 1998. Assessment of neotropical landbirds on 59. Sopuck, L., K. Ovaska, and B. Whittington. 2002. Respons- McChord Air Force Base, Washington. The Nature Conservan- es of songbirds to aerial spraying of the microbial insecticide cy of Washington, Seattle, unpublished Final Report submitted Bacillus thuringiensis var kurstaki on Vancouver Island, British to McChord Air Force Base. Columbia, Canada. Environmental Toxicology and Chemistry 21:1664-1672. 52. Stephens, J. L., I. J. Ausprey, N.E. Seavy, and J. D. Alexan- der. 2011. Avian and vegetation response to the Quartz wildfire, 60. Knight, R.L. 1979. Oregon White Oak Forest. Pp. 82 in 2001 – 2010. Klamath Bird Observatory unpublished report. Y:\ Forty-second Breeding Bird Census, W. Van Velzen (editor). KBO Library\Reporting\2011\2001-2010 Quartz\Stephens et American Birds 33:82. al. 2011 Quartz wildfire.pdf.

28 • Oak Bird Guide Appendix A. Oak Bird Species Accounts

Key to the Oak Bird Species Accounts and variable-radius data sets from the Willamette Valley, Umpqua Valley, and Rogue Basin: Population Status and Trends: BBS = Breeding Bird Survey www.mbr-pwrc.usgs.gov/ • 192 point counts at 8 point count stations during three bbs/trend/tf10.html years at Owens Farm in the central Willamette Valley (B. Altman unpublished data) NPR = Northern Pacific Rainforest is a Bird Conservation Region (BCR) that includes northwestern California (CA), • 56 point counts at 22 point count stations at nine sites western Oregon (OR), western Washington (WA), west- during one year in the central and southern Willamette ern British Columbia, and southeastern and southcoastal Valley (B. Altman unpublished data) Alaska. Oak habitat only occurs north to southwestern • 251 point counts at 15 point count stations during British Columbia, but some of the non-obligate oak bird three years at Coburg Hills in the southern Willamette species have data from BBS routes north of southwestern Valley (B. Altman unpublished data) British Columbia. Although California is not part of the • 33 point counts at 13 point count stations during one geographic scope of this document, population trend in- year at three sites in the central Willamette Valley (B. formation from California is included to assess its potential Altman unpublished data) effect on the entire BCR population trend. • 298 point counts at 101 point count stations during All statistically significant trends36 are in bold. For species one year at 11 sites throughout the northern Umpqua that are not obligate to oak habitats (most oak-associated Valley (Klamath Bird Observatory unpublished data) species), trends represent their status in all habitats in which they occur. • 332 point counts at 332 point count stations during one year throughout the Rogue Basin (Klamath Bird Nest Location and Timing: Observatory unpublished data) The locations and dates are those most typical for each species. There will be exceptions, and nesting dates can • 109 point counts at 109 point count stations (oak- vary some with latitude – nesting and finishing earlier conifer) during one year throughout the Rogue Basin in the Klamath Mountains, and later in the north Puget (Klamath Bird Observatory unpublished data) Lowlands and Georgia Depression. • 74 point counts at 74 point count stations (oak-hardwood) during one year throughout the Rogue Basin Breeding Range in Oak Habitats: (Klamath Bird Observatory unpublished data) The basic geographic scope of each species breeding range. However, nesting at a particular site or area within the Oak Habitat Conditions/Relationships: range is based on local and/or landscape factors. This summary only included results from studies in oak or mixed oak types during the breeding season that reported Comments: significant correlations between species abundance and Noteworthy observations relative to a species ecology or different habitat variables. We include some results from conservation that might be useful to a land manager. northern California studies because of the likely similari- Ecoregional/Sub-Regional Oak Habitat Density ties, especially in the Klamath Mountains ecoregion, and Estimates: to supplement limited data from Oregon, Washington, Ecoregional/sub-regional density estimates are based on and British Columbia. data as described in Appendix B. There was no data avail- dbh = diameter at breast height able for the Klamath Basin sub-region. Optimal Oak Habitat: Oak Habitat Type Regional Density Estimates: The habitat conditions (e.g., tree size, canopy cover, shrub Oak habitat type density estimates are regional mean cover) most suitable for the species in oak habitats. Spe- estimates based on a subset of data from Appendix B cies may occur outside these conditions in lesser quality that included an assessment of habitat type at point oak habitat. count stations. This includes the following fixed-radius

Oak Bird Guide • 29